Development of an instrument to measure nausea and vomiting in pregnancy.

Severity of nausea, retching and vomiting was determined using a newly developed nausea and vomiting in pregnancy instrument (NVPI) in two groups of pregnant women at two gestational time periods. Participants at Time 1 (approximately gestational week 9), completed a postal questionnaire (N = 643) and those at Time 2 (approximately 13 weeks) completed the instrument at the clinic (N = 284). The three scale items forming the instrument had acceptable internal reliability (Time 1 alpha = 0.76; Time 2 alpha = 0.82). It was noted that approximately 60% of women did not vomit, approximately 30% experienced no retching, but 30-40% experienced nausea either all the time or more than once a day. The instrument may prove to be useful as a research tool to study nausea and vomiting in pregnancy.